.omega.-3 Unsaturated fatty acids such as docosahexaenoic acid and eicosapentaenoic acid has been known to have various functions including inhibiting platelet aggregation, lowering a cholesterol level in blood, improving function of brain (see, Japanese Patent Laid-Open Hei 1-279827, Japanese Patent Laid-Open Hei 2-49723), and an antiallergic action. However, compared with .omega.-6 unsaturated fatty acids such as linolic acid, the .omega.-3 unsaturated fatty acid compound such as docosahexaenoic acid and eicosapentaenoic acid has an extremely inferior stability to oxidation, and it provides an unpleasant smell and taste, when it is oxidized, so it has been difficult to add it to a food, not to mention the use as a salad oil or a frying oil like safflower oil containing a large amount of linolic acid and the like. Accordingly, there have been various antioxidation means provided in order to utilize .omega.-3 unsaturated fatty acids such as docosahexaenoic acid and eicosapentaenoic acid as well as fats and oils containing them; the means include, for example, a process using an anti-oxidizing agent such as tocopherol and catechin, an encapsulation process using gelatin etc., and a process to fill an inactive gas. However, even by the use of the above-mentioned processes, the problem of long-term stability has not yet been cleared completely, and as for the ingestion, there are even such problems as an unpleasant feeling caused by the smell of the oxide and influence of the oxide on a human body. The antioxidation process and ingestion process for .omega.-3 unsaturated fatty acids such as docosahexaenoic acid and eicosapentaenoic acid as well as fats and oils containing them still have problems to be solved.